The Roof Diary – Roof Ventilation

The Roof Diary – Roof Ventilation


A few days ago, a home owner discovered that their roof was turning into a sauna a discovery that made them quite unhappy. For the home occupants to remain healthy and happy, the roof must also remain healthy, a hot roof is therefore an indication of an unhappy roof. Over the years, roof ventilation has been an area that continues to be overlooked which is counterproductive since the roof is the first line of defense for any building.

Roof ventilation does not only affect the roof but has a direct impact on your home’s heating and cooling system. During the cold season, roof ventilation will release any heat collected in your ceiling space, if this does not happen, the heat accumulates causing your ceiling to crack and impact your roof negatively. In warmer seasons, the heat will be trapped causing unnecessary angst to the occupants.

roof ventilation
Roof ventilation

Another overlooked danger of a poorly ventilated roof and ceiling space is moisture build up. Without an escape channel for air, trapped moisture can significantly damage the substructure of your roof. Left unattended, mold and mildew could develop, nails will rust or even break affecting your roof deck. A properly ventilated roof and ceiling space will provide a heat escape, preventing these costly mistakes.

Now that the dangers of poor ventilation are clear, you may wonder what exactly ventilation is. “Ventilate” comes from the Latin word for “to fan” this is the action of causing air to move. Therefore the principle of any efficient ventilation system on any type of building must provide a steady, high volume air movement channel. That means that the ventilation system used must be sized and positioned to provide a constant flow of air moving systematically in a constant direction.  Important to remember is that the net free intake area of vents should be greater than the exhaust venting.

There are several types of roof and ceiling ventilation methods and the one best method for your project should be discussed with your architect and contractor. The main types of ventilation system are:

  • Soffit vents and ridge vents: These two systems work in tandem. To achieve the ideal air circulation, there must be a point of air entry and a point of air exit. The soffit vents are fixed under the eaves for air entry while the ridge vents run along the highest peak of the roof providing an escape route for hot air and moisture in the ceiling space. Installing one without the other would therefore be ineffective, a mistake commonly seen on various buildings. The reliable application method for the soffit vents involves making holes on the eave board and covering them up with a vents panels.
  • Gable vents: These are found on either end of your roof, both on the lowest and highest side of the roof to create the balance required for cold air entry and hot air displacement.

Take a walk around your home and check if you have any of the above ventilation methods in place, if not you need not to worry as this can still be done with minimal interference to the occupants, giving you and your roof a smile and a longer happier life.


The author, Irene Wanjiku, is a roofing specialist most commonly known as ‘The Roofing Queen’ and Managing Director of Rexe Roofing Products Ltd. She can be reached on her Twitter page , Facebook page or

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.